Rolling mill work roll assemblies

ABSTRACT

A rolling mill work roll assembly comprises a work roll held in position on a hollow shaft member by the shaft member being in a stressed condition to exert radial loading and preferably also axial loading on the work roll. The grip is sufficient to transmit normal driving torque. The hollow shaft is operated by hydraulic pressure means which acts internally to lengthen the bolt and shrink its diameter to permit ready assembly and disassembly. The roll is preferably composite, that is it comprises a tungsten carbide rolling ring supported on each side by steel sleeves.

Elnfited States Patent 1191 Oxlade ROLLING MILL WORK ROLL ASSEMBLIES [75] Inventor: Roy R. Oxlade, London, England [73] Assignee: The British Iron and Steel Research Association, London, England 22 Filed: Dec. 3, 1969 21 Appl. No.: 881,801

[30] Foreign Application Priority Data Dec. 10, 1968 Great Britain 58650/68 [52] US. Cl. 29/125, 29/129.5 [51] Int. Cl B2lb 31/08 [58] Field of Search 29/110, 125, 129.5, 123, 29/148.4 D

[56] References Cited UNITED STATES PATENTS 228,842 6/1880 Totten 29/129.5 983,828 2/1911 Lentz 29/125 1,938,995 12/1933 Beynon..... 29/129.5 2,018,247 10/1935 Biggert et a1. 29/129.5 2,342,159 2/1944 Moran 29/125 1 Apr. 16, 1974 3,111,742 11/1963 Lakin 29/125 3,426,414 2/1969 3,461,527 8/1969 2,964,251 12/1960 Samuels et a1 29/129.5 UX 3,577,619 5/1971 Strandell 29/148.4 D

Primary Examiner-Alfred R. Guest Attorney, Agent, or Firm-Sughrue, Rothwell, Mion, Zinn & Macpeak [5 7] ABSTRACT A rolling mill work roll assembly comprises a work roll held in position on a hollow shaft member by the shaft member being in a stressed condition to exert radial loading and preferably also axial loading on the work roll. The grip is sufficient to transmit normal driving torque. The hollow shaft is operated by hydraulic pressure means which acts internally to lengthen the bolt and shrink its diameter to permit ready assembly and dis-assembly. The roll is preferably composite, that is it comprises a tungsten carbide rolling ring supported on each side by steel sleeves.

5 Claims, 4 Drawing Figures PATENTEUAPR 16 1924 SHEET 1 OF 3 Q NP Om Ow l Nv we mm 0? ROLLING MILL WORK ROLL ASSEMBLIES This invention relates to work roll assemblies for use in rolling mills. Particular applications for assemblies according to the invention may be found in two high or in four or more high rod or bar mills, embodiments of the latter being disclosed for example in our copending Patent Application Nos. 775,840; 775,593 and 775,668.

It is generally desirable that mill work rolls be removable so that they can be exchanged for different rolls to permit a variety of rod or bar sizes and shapes to be rolled on the same mill and also to permit worn rolls to be replaced. The work rolls are accordingly removably carried on roll drive shafts which are rotatably mounted and driven in'the mill frame. The mounting of the roll on the shaft so as to facilitate the ready removal thereof whilst still enabling the roll to withstand the heavy rolling loads without damage to the mounting or shaft is a continuing problem for the mill designer.

An object of the invention is accordingly to provide a work roll assembly which is readily removable from the drive shaft.

According to the present invention there is provided a rolling mill work roll assembly comprising a work roll drive shaft and a work roll, said work roll including a ring or sleeve member formed to define a rolling groove or surface of the work roll, said ring member being radially and axially located with respect to a coaxial hollow shaft member which is co-axially secured to or formed integrally with said drive shaft, said hollow shaft member being in a stressed condition to exert radial loading or axial loading or both or said work roll whereby to provide respectively said radial location or axial location or both of said ring member.

In prefered embodiments of the invention the work roll comprises said ring member supported on both sides by sleeve members. Accordingly the ring member may be of, e.g., tungsten carbide and the sleeve of, e.g., steel. Tl-Ie tungsten carbide provides a long, accurate roll groove life, which resists wear, thermal shock and rolling fatigue. Theroll groove thus has the advantages of tungsten carbide but the 'roll as a whole is not, so heavy. or as expensive as a solid tungsten carbide roll would be. Moreover if the ring member is damaged, it is readily replaceable, without the necessity of replacing the steel sleeve member. A damaged tungsten carbide solid roll would have to be scrapped as a whole. The provision of a composite roll in this manner which can readily be dis-assembled, also provides the advantages of ease of handling, and the storage bulk of the mill inventory of different groove size rolling members is reduced. Finally the composite roll can, in some forms, be more adequately cooled in use.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

generally at 10 and 11, and a ring or sleeve member 12 provided with a single circumferential rolling groove 13. The sleeves have axial bores 14 and 15. The first sleeve has an outer end portion presenting a recess 16 for a purpose to be described below. The inner end portion of the first sleeve presents an annular seat 17 accurately perpendicular to the roll axis, and a vestigial spigot 18 radially inward of the seat 17.

The second sleeve 11 has an outer end portion adapted to locate the roll axially and radially on a work roll shaft as will be explained below. The inner end portion of the second sleeve presents an annular surface 20 perpendicular to the roll axis, and a frusto conical spigot 21 radially inward of the seat 20. Spigot 21 converges away from the sleeve 11 and terminates in an annular face 22 opposed to an annular face 23 presented by the end face of the spigot 18.

The ring member 12 has a constant cross-section in the general shape of a trapezium. The parallel annular side faces 30, 31 are perpendicular to the roll axis. The axial length of the ring is equal or marginally less than the summed axially lengths of spigots l8 and 21.

The inner surface of the central aperture of the ring 12 is a frusto conical surface 32 over the major portion of its axial length, the cone angle, axial length and datum diameter of surface 32 being substantially equal to the corresponding external dimensions of spigot 21. The remainder of the inner surface of the central aperture of ring 12 is a cylindrical surface 33 substantially equal in diameter and axial length to the diameter and axial length of spigot 18.

Two diametrically opposed pairs of registering axially directed key-ways 40, 41 are provided, the key-ways of each pair being formed in the inner surface of the ring 12 and in the outer surface of the spigot 21. A key member 42 is shaped for sliding movement into each said pair of key-ways.

The outer end portion of the second sleeve 1 l is constructed in the same manner as the equivalent end portion of the work roll particularly described in and with reference to FlGS. 2 and 3 of the drawings of our copending Patent Application No: 52086/67. Briefly the end portion presents an axial recess 50 shaped to receive a work roll shaft spigot, an annular seating surface 51 radially outward of the recess 50, and a curved wall key member 52 extending circumferentially of the part 11 to slightly less than of the roll circumference. Recess 50 locates the roll radially on the shaft spigot, surface 51 locates the roll axially on the shaft seat, and key member 52 mates with a key-way and an optional wedge associated with a work roll shaft substantially to prevent backlash between the roll and its shaft.

In use the threeparts 10, 11 and 12 of the work roll, and key members 42, are assembled as shown in the drawings. The work roll is then mounted to a work roll shaft by means of a hydraulic hollow bolt (not shown) extending from within an axial bore in the shaft and through bores 14 and 15 of the work roll. A nut is threaded on the end of the bolt. A radial face of the nut bears against the annular face within the recess 16 of part 10. When the nut has been tightened on the bolt and the bolt has been de-pressurised to relax into a state of considerable axial tension, it will be seen that the parts 10, ll of the roll are urged axially together into pre-loaded engagement. The annular seat 17 on part 10 provides axial support and location in one axial direction for the ring shape part 12. Support and location for part 12 in the other axialdirection is provided basically by tapered spigot 21 engaging tapered surface 32 of ring 12. This latter engagement also provides radial support and location for ring 12 on part 11. Parts and 12 are located radiallyby the engagement of vestigial spigot 18 and surface 33. Backlash between ring 12 and part 11 which is the driven part of the roll is substantially prevented by friction assisted by key members 42, which also serve to drive the ring '12.

The support parts 10 and 11 would normally be of steel ,and the ring member 12 of tungsten carbide. An advantage of this embodiment is thus that the ring member 12, which is the part containing the groove 13 and thus most subject to wear in use, can be made of considerably harder and longer lasting material than the remainder of the work roll. Expense of making the whole roll of hard wear resistant material is thus avoided, and similarly it may be possible to achieve a work roll whose support parts 10, 11 and ring 12 wear at substantially the same rate, although part 12 is subject to greater wear in use. Moreover the roll is separable into parts and thus a worn ring can readily be replaced. ln addition the ring 12 can readily be replaced by a ring defining a different shaped rolling groove 13. In another embodiment ring 12 may be provided with two or more rolling grooves.

Furthermore tungsten carbide is approximately twice as heavy as steel, so the weight of a solid tungsten carbide rollwould render the roll difficult to handle. Finally, parts 10 and 11, which in use roll on a back up roll surface, could be formed of a fatigue resistant steel not suitable for roll groovematerial but with longer life when serving only to define a back up work roll contact surface.

If necessary, instead of or in addition to keying, the roll part may be glued or brazed together and/or the roll may be glued or brazed to the drive shaft.

Referring now to FIG. 2 there is shown a longitudinal section of a work roll assembly for a four or more high rod or bar mill comprising a work roll mounted on a hollow shaft member 60 secured to a drive shaft 61. The work roll comprises a ring member 62 defining a rolling groove 63. The ring member 62 is axially located and supported-by two sleeve members 64, 65. The three members 62, 64, 65 are mounted on hollow shaft member 60 which has a threaded end portion 66 received in a threaded recess 67 in the end of the drive shaft 61. A head flange 68 on the hollow shaft member engages sleeve 64, and an annular seat 69 on the end of shaft 61 engages sleeve 65. Consequently flange 68 and seat 69 provide axial location in both directions for the. work roll. 7

The member 60 serves as a form of hydraulically expansible bolt. In its unassembled unstressed state its diameter is slightly greater than the'diameter of the bore through the parts of the composite work roll. In order to insert the member 60 through the bores, the member 60 is axially stretched by hydraulic pressure means acting internally thereof. The axial stretching is accompanied by a diametrical shrinkage sufficient to permit the three roll parts to be mounted on the member 60. The member 60 is then threaded into the drive shaft 61 and tightened thereon by simple mechanical means, that is, no special effort is made to tighten it very securely. The hydraulic pressure within the hollow is then released, thus causing the member 60 to expand in diameter, so

far as it is able, and to shrink in axial length, to assume a stressed condition.

The diametrical expansion causes the member to exert substantial radial loading on the work roll members 62, 64 and 65 whereby to locate them radially (provided their relative bore diameters are correctly chosen in relation to the bolts diameter); and the axial shrinkage causes the member 60 to exert substantial axial loading on the work roll members by means of flange 68 and seat 69.

It should'be noted that the threaded portion on the'head of the hollow shaft member 60 serves for attachment of a valved pressure device through which the hydraulic fluid is forced to build up on the head of a plunger. The tail of the plunger engages the inner end of the hollow, whereby to cause the hydraulic pressure to act directly to stretch the bolt and permit its diameter readily to shrink as described. When in use the hollow in the bolt is protected from dirt by a dust cap shown e.g., at 88 in FIG. 3.

If desired additional location can be afforded by keying means, such as mating spigots, on the roll members and the drive shaft, one such being shown schematically at 70.

The torsional drive of the roll is transmitted by virtue of a combination of the axial clamping force and the radial grip which effectively also comprehends circumferential location by friction. The drive from the drive shaft 61 to the roll is provided by the key 71, similar to that described in relation to FIG. 1. If desired two or more similar keys spaced circumferentially may be used. The torque transmission capability can be enhanced, if desired, by keying means acting between the assembled parts, e.g., knurling the outer surface of the member 60, providing keys between the roll sleeves, or by glueing or brazing mating surfaces of the roll sleeves, or the outer peripheries of the three members 64, 64 and 65 can be provided with mating noses and recesses.

Referring now to FIG. 3, two embodiments are shown in the upper and lower halves of the drawing respectively. In each embodiment a hollow shaft member acts in a similar manner to the hollow shaft member 60 described in relation to FIG. 2, except that in this case it is formed integrally with the drive shaft 61. Consequently it is not possible to place the work roll sleeves 81, 82 and 83 on the hollow shaft member from the right hand end thereof. In the upper half of the figure the valved pressure device, which threads on the head 84 of the hollow shaft member, is of larger diameter than the bore of the sleeves 81, 82 and 83. Thus the sleeve cannot be mounted from the left hand end when the member 80 is pressurised.

To solve this difficulty the hollow shaft member is either given a gradual taper, (not shown) or is stepped as shown at 85 and 86. The sleeves are of appropriate internal diameters as shown. To assemble the assembly, the sleeves are placed on the unpressurised unstressed member 80 onto diameters displaced one step to the left of their final position. The valved pressure device can then be attached to threaded portion 84 and the member pressurised. The sleeves can then be moved one step to the right onto their final positions as shown, and the bolt then de-pressurised to assume a stressed condition to provide location as described above in relation to FIG. 2. In this case a nut 87 or other locking device serves the purpose of flange 68.

In the lower half of FIG. 3 the inner diameter of the hollow shaft member 80 is threaded at 89 and the valved pressure device for use in pressurising the bolt is dimensioned to be wholly of less diameter than the bores of the sleeves. Consequently the sleeves can then be placed in position on the member 80 over the pressure device, thus avoiding the need for steps 85 and 86.

Referring now to FIG. 4, there is shown a work roll assembly for a two high mill, and four embodiments are partly illustrated in this Figure.

In the first embodiment a plurality of work roll grooved rings 90 are spaced along a hollow shaft member 91 and are maintained in position, radially and axially, simply by the stressed condition in member 91 exerting sufficient radial loading thereon. The torque transmission capability can'be enhanced if required by knurlirig the member 91 or providing flats or keys between the ring bore and the member 91, or by glueing or brazing the rings to the member 91. Cooling of this embodiment would be very efficient since cooling fluid could penetrate the annular grooves between adjacent rings 90. i

The hollow shaft member is shown as formed integrally with a'drive shaft 92 and is supported for rotation on two chocks 93, provided with suitable roller bearings 94. The chocks and member 91 are axially mutually located by virtue of the slow taper of shaft portions 95, and by end nuts 96.

FIG. 4 also shows, in its lower half, rings 90 spaced by spacing rings 97. The sequence of alternate rings 90 and 97 are axially clamped and located between a flange 98 on the member 91 and a nut 99, which is tightened before de-pressurising of the hollow shaft member 91 in a similar manner as described before. In this embodiment, of course, the radial loading by member 91 is not essential, since the axial loading and location can be sufficient to transmit the necessary torque.

This Figure also shows rings 90 spaced by spacing rings 100 which are trapezium shaped in crosssection and taper inwardly, the taper matching outer bevels 101 on the rings 90. Spacing rings 102 are also shown, which are trapezium spaced and taper outwardly, the taper matching undercut bevels 103 on the rings 90. The rings 100 are usually preferable since their hoop stress in use exerts compression on the rings 90, whereas rings 102 cause extra tension in rings 90. When the rings 90 are of tungsten carbide, compressional forces are more suitable to the material. In the latter two embodiments the angles of the trapezium are chosen to compensate for any difference between the co-efficients of thermal expansion of the material of the work roll rings and the material of the hollow shaft member.

Many advantages of the above described embodiment have already been given, but finally it should be noted in addition that the use of composite work rolls which are radially loaded or axially loaded, or preferably both, by a stressed hollow shaft member, leads to a stiffer work roll assembly (where stiffness means the deflection of a selected point per unit load) than many of the assemblies in use at the present time.

The drawings have shown work rolls with rolling grooves. In applying the invention to flat strip mills, the work rolls would have cylindrical rolling surfaces instead of the grooves.

I claim:

1. A rolling mill work roll assembly comprising a hollow shaft member which is coaxially secured to or formed integrally with a work roll drive shaft and which extends coaxially in a bore of a work roll, said work roll including an annular member formed to define a rolling groove or surface of the work roll, said shaft member having a first end face and an axial hollow in said shaft member open at one end onto said first end face and closed at the other end, said closed end of said hollow constituting a first reaction surface, means integral with the shaft member adjacent said open end of said hollow to provide a second reaction surface, whereby said hollow shaft member is adapted to be axially stretched by load applying means acting on and between said first and said second reaction surfaces to cause sufficient diametrical reduction of said hollow shaft to permit insertion and removal thereof into and from its assembled position in said work roll bore, said shaft member when not so stretched having a diameter too large to permit such insertion and removal, said shaft member thereby exerting both radial loading outwardly on said work roll and axially compressive loading between the axially opposite end faces of the work roll, whereby to provide respectively radial and circumferential location and longitudinal location of said work roll with respect to said hollow shaft member.

2. An assembly as claimed in claim 1 wherein said work roll comprises at least two sleeve members disposed on said hollow shaft member one at each side of said annular member in engagement therewith and exerting axial loading thereon.

3. An assembly as claimed in claim 2 wherein the interfaces of the annular member and the sleeve members are provided with mutual keying means, whereby to ensure the members rotate together under high torque loading.

4. An assembly as claimed in claim 1 wherein said hollow shaft member has a portion presenting a radial surface and said work roll has a radial end face, said radial surface exerting axial loading on said radial end face of the work roll.

5. An assembly as claimed in claim 1 wherein said hollow shaft member has an externally threaded portion, and wherein a nut is provided in said threaded portion to exert loading on a radial end face of the work roll. 

1. A rolling mill work roll assembly comprising a hollow shaft member which is coaxially secured to or formed integrally with a work roll drive shaft and which extends coaxially in a bore of a work roll, said work roll including an annular member formed to define a rolling groove or surface of the work roll, said shaft member having a first end face and an axial hollow in said shaft member open at one end onto said first end face and closed at the other end, said closed end of said hollow constituting a first reaction surface, means integral with the shaft member adjacent said open end of said hollow to provide a second reaction surface, whereby said hollow shaft member is adapted to be axially stretched by load applying means acting on and between said first and said second reaction surfaces to cause sufficient diametrical reduction of said hollow shaft to permit insertion and removal thereof into and from its assembled position in said work roll bore, said shaft member when not so stretched having a diameter too large to permit such insertion and removal, said shaft member thereby exerting both radial loading outwardly on said work roll and axially compressive loading between the axially opposite end faces of the work roll, whereby to provide respectively radial and circumferential location and longitudinal locatioN of said work roll with respect to said hollow shaft member.
 2. An assembly as claimed in claim 1 wherein said work roll comprises at least two sleeve members disposed on said hollow shaft member one at each side of said annular member in engagement therewith and exerting axial loading thereon.
 3. An assembly as claimed in claim 2 wherein the interfaces of the annular member and the sleeve members are provided with mutual keying means, whereby to ensure the members rotate together under high torque loading.
 4. An assembly as claimed in claim 1 wherein said hollow shaft member has a portion presenting a radial surface and said work roll has a radial end face, said radial surface exerting axial loading on said radial end face of the work roll.
 5. An assembly as claimed in claim 1 wherein said hollow shaft member has an externally threaded portion, and wherein a nut is provided in said threaded portion to exert loading on a radial end face of the work roll. 